package dome1.textdome;

import java.util.LinkedList;
import java.util.Queue;

class MyStack {
    private Queue<Integer> qu1;
    private Queue<Integer> qu2;

    public MyStack() {
        qu1 = new LinkedList<>();
        qu2 = new LinkedList<>();
    }
    
    public void push(int x) {
        if(empty()){
            qu1.offer(x);
            return;
        }
        if (!qu1.isEmpty()){
            qu1.offer(x);
        }else{
            qu2.offer(x);
        }
    }
    
    public int pop() {
        if (empty()) {
            return -1;
        }
        if ((!qu1.isEmpty())) {
            int size = qu1.size();
            for (int i = 0; i < size - 1; i++) {
                qu2.offer(qu1.poll());
            }
            return qu1.poll();
        } else {
            int size = qu2.size();
            for (int i = 0; i < size - 1; i++) {
                qu1.offer(qu2.poll());
            }
            return qu2.poll();
        }
    }

    public int top() {
        if (empty()) {
            return -1;
        }
        if ((!qu1.isEmpty())) {
            int size = qu1.size();
            int tmp = -1;
            for (int i = 0; i < size; i++) {
                tmp = qu1.poll();
                qu2.offer(tmp);
            }
            return tmp;
        } else {
            int size = qu2.size();
            int tmp = -1;
            for (int i = 0; i < size; i++) {
                tmp = qu2.poll();
                qu1.offer(tmp);
            }
            return tmp;
        }
    }

    public boolean empty() {
        return qu1.isEmpty() && qu2.isEmpty();
    }
}